JPS62178063A - Image reader - Google Patents

Abstract

PURPOSE:To make continuous variable magnification possible and make a device low-cost and compact by making the read pulse of a solid-state image pickup element and the driving pulse of a stepping motor asynchronous with each other. CONSTITUTION:At the time of a start key is depressed, originals 2 are sent to an image reading part one by one, and the original is illuminated with a light source while passing between two pairs of carrying rolls 4 and 5, and the reflected optical image is led to a solid-state image pick-up element 10 through a mirror 8 and a lens 9 to read the picture of the original 2. Since the driving pulse of a stepping motor 11 and the read pulse of the element 10 are made asynchronous with each other, the continuous variable magnification can be made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image reading device used in copying machines, facsimile machines, and the like.

(Prior Art) Conventionally, there is an image reading device of this type as shown in FIG. In this method, two sets of a conveyance roller 22 and a facing roller 23 are placed in pressure contact with each other at a predetermined interval on the conveyance path of the document 21, and the document 21 is is conveyed by pinching it. Then, the image of the original 21 is illuminated by the light source 24, and the reflected light image is transmitted to the CCD via the mirror 25 and lens 26.
etc., and reads the image of the original 21.

The conveying rollers 22.22 are rotationally driven at a predetermined speed by transmitting the rotational driving force of the stepping motor 29 through the belt 30 via the variable speed a28.

At this time, as shown in FIG.
The reading pulse and the driving pulse of the stepping motor 29 are synchronized. In order to change the magnification of the image on the original 21, it is necessary to change the feeding speed of the original 21.
8 or by changing the drive pulse.

However, in this case, there was a problem that the magnification ratio was limited because the reading pulse and the driving pulse had to be synchronized6.Therefore, in order to solve the above problem, the As shown, there is also one that uses a C servo motor 31 as a drive source, which allows continuous speed control. The structure L of this DC servo motor 31 makes it impossible to control the speed at the time of starting, so a clutch 32 is required when precision is required in intermittent operation. That is, D.C.
To perform intermittent driving using the servo motor 31,
The motor is driven continuously, and the driving force is intermittent by the clutch 32.

(Problem to be solved by the invention) However, in the case of such prior art, DC is used as the driving source.
Since the servo motor 31 is used, the drive of this DC servo motor 31 is controlled.

A complex or rose droop control circuit such as phase-locked loop (PLL) control is required, which poses a problem in that the device becomes expensive and large.

The present invention has been made to solve the problems of the prior art described above, and its purpose is as follows.

It is an object of the present invention to provide an image reading device that is capable of stepless magnification, and is capable of reducing costs and making it more compact.

(L Stage for Solving Problems) The present invention provides the following features: [In order to achieve the first objective, the reading means for reading an image of the original document and the reading L stage are moved relative to each other, and the reading means In an image reading device that reads an image of a document using a solid-state image sensor installed in the image sensor, a stepping motor is used as a driving source for relatively moving the document and the reading means, and a stepping motor is used to send a reading pulse to the solid-state image sensor and a stepping motor. The motor drive pulses are configured to be asynchronous.

(Function) In the present invention, the magnification of the read image is changed by arbitrarily changing the frequency of the driving pulse of the stepping motor.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows an embodiment of an image reading device according to the present invention. In FIG. A conveyance path 3 for the document 2 is formed. In the conveying path 3, two sets of conveying rollers 4 and opposing rollers 5 are arranged at a predetermined interval, and these conveying rollers 4,
4 and opposing rollers 5, 5, the original 2 is nipped and conveyed.

When the original 2 passes between the transport rollers 4.4, it is illuminated by light rA7 from the opening 6 of the guide plate 1, and the reflected light image is transmitted to a solid-state image sensor 10 such as a CCD via a mirror 8 and a lens 9. The image of the document 2 is read by the solid-state image sensor 10. The above light [7, mirror 8. The lens 9 and the solid-state image sensor 10 constitute a reading means. A stepping motor 11 is used as a driving source for rotationally driving the conveying roller 4, and the driving force of this stepping motor 11 is transmitted through a driving pulley 12 and a belt 13 connected to the stepping motor ll by the Confederate Army. and is transmitted to the conveyance rollers 4, 4.

In the above configuration, the image reading apparatus according to the present embodiment reads an image of a document in the following manner. That is, when a start key (not shown) is pressed, the originals 2 are fed one by one from the original stacking section (not shown) to the image reading section.

This document 2 is carried by two sets of transport rollers 4, 4 that are in pressure contact with each other.
While passing between the document 2 and the facing roller 5.5, the document 2 is illuminated by a light source 7, and the reflected light image from the document 2 is guided to the solid-state image sensor 10 via the mirror 8 and the lens 9. The image of the original 2 is read.

At this time, the 11 pulse of the stepping motor 11 and the reading pulse of the solid-state image sensor IO are in an asynchronous state, as shown in FIG. When changing the magnification, the magnification of the document 2 in the feeding direction is changed by changing the driving pulse of the stepping motor 11 independently of the reading pulse of the solid-state image sensor 1o, and enlarging or reducing the document 2. In this way, it has been confirmed that even if the driving pulse of the stepping motor 11 and the reading pulse of the solid-state image sensor 1o are asynchronous, there is no problem in actual images.

In the embodiment shown in FIG. 1, a case has been described in which the original M42 is moved, but it goes without saying that the present invention can also be applied to a case in which the original is fixed and the reading stage is moved.

(Effects of the Invention) The present invention has the above-described configuration and operation, and by making the reading pulse of the solid-state image sensor and the driving pulse of the stepping motor asynchronous, stepless magnification is possible, which is not necessary in the past. This makes it possible to use existing transmissions and clutches, making it possible to downsize and reduce costs.

[Brief explanation of drawings]

FIG. 1 is a schematic front view showing an embodiment of the image reading device according to the present invention, FIG. 2 is an explanatory diagram showing the reading pulses of the solid-state image sensor and the driving pulses of the stepping motor of the same device, and FIG. 3 is the conventional image reading device. FIG. 4 is an explanatory diagram showing the reading pulses of the solid-state image sensor and the driving pulses of the stepping motor of the same device, and FIG. 5 shows another embodiment of the conventional image reading device. It is a schematic front view. Explanation of symbols 2...Manuscript 7...Light source 8...Mirror 9...Lens 10...Solid-state image sensor 11...Stepping motor patent applicant Canon Corporation.

Claims (1)

[Claims] In an image reading device that relatively moves an original and a reading means for reading an image of the original, and reads the image of the original with a solid-state image sensor provided in the reading means, the original and the reading means are relatively moved. An image reading apparatus characterized in that a stepping motor is used as a driving source for the image sensing, and a reading pulse to the solid-state image sensor and a driving pulse of the stepping motor are asynchronous.